Altenburg Castle sits atop Bamberg's highest hill, offering the best panoramic views of the city and Franconian countryside. First mentioned in 1109 as a refuge, it became a richly furnished residence for Bamberg's bishops in the 14th-15th centuries. The only remains of the medieval construction are the 33-meter keep from the 13th century and parts of the surrounding wall. You can climb the tower for just 1 Euro for unforgettable views. The castle grounds include a restaurant and are a popular destination for hiking from the city center.